The invention is directed to a heat-fed printing press and to a rotation printing press each respectively having at least one high-performance printing unit that, in particular, is a laser printing unit.
Laser and LED printers are currently distinguished by high-printing performance and printing quality in black-and-white printing. Printing performances of more than 50 pages per minute as well as a printing quality that comes close to that of offset printers are possible. Moreover, the manufacture and the operation of such printers are comparatively cost-beneficial. By contrast thereto, the technical pre-conditions for full-color laser printing are extremely involved and the on-going printing costs are very high.
Ink printers, also called ink jet printers, are often employed in conjunction with personal computers and in plotters since they cost-beneficially enable qualitatively high-grade color prints. The printing speeds obtainable with ink printers, however, are far, far lower then given laser printers so that ink printers have not yet been taken into consideration for the high-performance area.
JP-A-8 221 233 discloses a sheet-fed printing press with a plurality of printers that are respectively arranged at one of a plurality of parallel sheet transport paths. At their input side, these sheet transport paths are connected to a common sheet input path via sheet shunts. At the output side, the sheet transport paths are connected to a common sheet output path via sheet intermediate stores. The parallel arrangement of printing units serves the purpose of nonetheless being able to continue the printing process with the further available printing units given outage of one of the printing units. The printing of a sheet by at least two printing units is not addressed in this document. A bypassing of one of the printing units arranged parallel and a delivery of the sheets directly to the sheet output paths is also not disclosed in this document.
U.S. Pat. No. 5,140,674 discloses a serial arrangement of a color printer and a following monochromatic printer. Both printers print the same sheet, two-color printing being possible as a result thereof The serial arrangement of the two printers leads thereto that the printing unit with the lowest printing speed defines the speed of the printing process and, thus, the throughput of sheets.
EP-A-0 737 570 discloses a printing press with a plurality of printing units. These printing units are arranged serially following one another, i.e. the overall printing speed and the throughput of sheets is defined by the printing unit with the lowest printing speed. The printing units can also work according to different printing processes.
An object of the invention is to create a printing press that allows a fast, unproblemmatical and economical multi-printing and that can be simply and cost-beneficially manufactured.
The object is achieved by a sheet-feed printing press having at least one high-performance printing unit and a second printing unit with a common input and a common output. The second printing unit has a plurality of parallel sheet conveying paths which are connected at an input side to a common sheet input path via sheet shunts and the common sheet input path is connected to the input of the second printing unit, each of the plurality of sheet conveying paths has a multi-color or ink printing unit and discharges into a common sheet output path. The second printing unit also has a plurality of intermediate stores for sheets which are connected to the common output side and discharge into a common output path or transport path extending to the output of the second printing unit and the common sheet output path or transport path is connected by a shunt to the common sheet input path so that a sheet can be supplied to the common sheet output path while bypassing the multi-color printing units.
The invention makes it possible to unite the advantages of laser printing technology in black-and-white printing with the advantages of ink jet printing technology in color printing. In particular, mixed prints with text in black-and-white and additional, colored elements can be manufactured extremely economically.
Different color printing loads can be effectively buffered, so that the maximum speed prescribed by the laser printer can be adhered to over broad ranges. When the required color printing performance exceeds the performance capability of the ink or multi-color printing units, then the overall printing performance is not reduced discontinuously, as given conventional systems, but more or less continuously.
The invention can be employed not only given printers having a single laser printing unit but, for example, also given two-color laser printers in order to be able to implement an additional, full-color or partial-color printing. For example, laser-printed documents can be additionally provided with color accents, color backgrounds, chromatic, true-to-color company logos, negative entries in invoices in red or with the image of a company employee. The analogous case applies to single-color or two-color offset printing presses that are inventively equipped with additional ink printing units.
The ink printing units are preferably multi-color printing units but can also be organization color printing units, i.e. printing units for single-color where multi-printing without color mixing, what is referred to as a spot color printing. However, even in the case of predominantly spot color printing, multi-color printing units capable of color mixing are preferred, so that no complicated changes of color are required.
The sheet intermediate stores that compensate different printing speeds must in turn output the sheets input thereinto in an unaltered sequence. For example, stack sheet stores and shed sheet stores, whereby shed sheet stores work faster then stack sheet stores but generally have less capacity. In the preferred embodiment, a stack sheet store and a plurality of shed sheet stores are employed in common. In this way, extremely different printing jobs can also be carried out.
The sheets printed in the ink printing units can, as needed, be conducted to the various sheet intermediate stores when the plurality of parallel sheet transport paths discharge into the first common conveying or transport path that is connected to the plurality of sheet intermediate stores via further sheet shunts.
In a preferred embodiment of the invention, the sheet delivery to the ink printing units ensues via two-way shunts that are located in the common sheet input path of the ink printing units. The two-way shunts has a first output path that is connected via at least one further sheet shunt to the plurality of parallel sheet transport paths and has a second output path that discharges into the second common sheet output path of the sheet intermediate stores.
In the preferred embodiment, a sheet output path of the at least one high-performance printing unit is connected to the common sheet input path of the ink printing units, i.e. the ink printing units are arranged following the last high-performance printing unit in the sheet conveying direction. In this case, the common sheet output path of the sheet intermediate stores is, for example, connected to a final sheet store or to a means for sheet post-processing. Further, a control character sensor for control characters printed on the sheets by the high-performance printing unit can be arranged at the sheet output path of the at least one high-performance printing unit. The control characters can represent printing information for the ink printing units and/or sheet routing information for the sheet shunts.
For controlling the at least one high-performance printing unit and the plurality of ink printing units, either a common control unit is provided or each ink printing unit has a separate control unit that is connected to a main control unit of the printing press and controlled by this.
In the preferred embodiment, each ink printing unit forms an assembly together with a sheet conveying means that can be attached to the printing press or, respectively, removed therefrom independent of other assemblies. These assemblies and, as warranted, the ink printing units accommodated therein as well are identically constructed, so that they are interchangeable with one another.
The at least one high-performance printing unit, on the one hand and the ink printing units, sheet intermediate stores and sheet shunts, on the other hand, can be respectively accommodated in a separate housing, whereby the housing with the plurality of ink printing units is a removable attachment of the housing with the at least one high-performance printing unit. In this way, already existing printers can already be retrofitted with the invention. Corresponding devices that are already present in the housing with the at least one high-performance printing unit can be employed as final sheet store or as means for sheet post-processing.
Given a rotation printing press having a conveying path formed by rollers for a paper web and at least one-performance printing unit arranged at the conveying path, the aforementioned object is inventively achieved by a plurality of ink printing units that are arranged at intervals in a row along the conveying path, and in that a paper web intermediate store is located in the conveying path preceding each ink printing unit in paper conveying direction.
The paper web intermediate stores enable a speed compensation between the high-performance printing units and the ink printing units, whereby a plurality of ink printing units work in parallel. An even better adaptation to the greatest variety of different printing situations is enabled in that each printing unit has a drive for movement in the paper conveying direction.
Loop-forming devices are preferably employed as paper web intermediate stores, these being respectively composed of two stationarily seated deflection rollers and of an 180xc2x0 deflection roller, whereby bearing locations of the 180xc2x0 deflection roller are connected to a drive for moving the 180xc2x0 deflection roller in the direction to the stationarily seated deflection rollers and away therefrom.
The developments described in conjunction with the inventive sheet-fed printing press are also partly possible and advantageous given the inventive rotation printing press.